Blood borne diseases such as AIDS and Hepatitis present significant risks to medical personnel administering vascular injections. The means by which a patient's vessel and skin are pierced to either draw or introduce fluids can just as effectively pierce the hands and arms of attending medical personnel. Gloves or similar protective garb may provide some protection, but making such items entirely resistant to needle penetration oftentimes sacrifices the wearer's mobility and dexterity proportionate to the degree of protection. Therefore, protective wear is not a total answer to the problem.
In order to adequately protect medical personnel from inadvertent puncture and wounding, catheter systems have been developed to cover and shield the distal needle point after its withdrawal from the patient. These systems have taken a number of embodiments and have various degrees of elaboration. One such mechanism includes a cylindrical sheath of plastic which telescopes out from the flash chamber to surround the needle shaft, including the distal tip. Such mechanism increases costs of manufacture substantially and may malfunction, especially in a fluid filled environment where it may stick or slip. The need for locking parts under these circumstances also increases risk of failure. Other types of needle caps require moving parts, such as a spring activation, to close off the needle in the cap after its withdrawal. These sometimes combine moving parts with specially tooled needles having two or more separate widths so that the larger circumference and diameter either trips the spring and/or blocks the needle's removal from the cap.
Given that the needle protector, however configured, will be contaminated upon each use, cost-benefit requirements dictate that a desirable shielding system be disposable along with the needle. Furthermore, the system must be quick and easy to use as to present as little imposition as possible to the administration and function of the catheter. Moving parts which may malfunction or stick such as springs and similar biasing mechanisms, as well as telescoping sheaths requiring deployment from the flash chamber, are less desirable in this regard and can drive up the manufacturing cost for a disposable unit. Lathering the needle circumference to alter the circumference over particular segments requires precise tooling and hence substantially added cost. The further requirements for sealing the system against fluid leakage and backflow may also show such designs to be problematic.
Therefore, it is desirable that a protective system be simple and dependable in its is deployment, cheap to manufacture, expedient in its operation and effective in sealing off the distal point and preventing fluid leakage or backflow.